Steam generator and other heated heat transmitters

ABSTRACT

The steam generator is provided with a whirling combustion chamber capable of generating at least 107 kcal./cubic meter hour ata. The whirling combustion chamber is connected directly to a combustion gas flue containing heating tubes or surfaces therein. The walls of the combustion chamber do not require cooling means as such are lined with ceramic oxide material.

United States Patent Inventor Harendra Nath Sharan Zurich, Switzerland Appl. No. 875,857

Filed Nov. 12, 1969 Patented Sept. 14, 1971 Assignee Sulzer Brothers, Ltd.

Winterthur, Switzerland Priority Sept. 26, 1969 Switzerland 14542/69 STEAM GENERATOR AND OTHER HEATED HEAT TRANSMI'I'I'ERS 9 Claims, 1 Drawing Fig.

US. Cl .1 122/235 R,

431/158 Int. Cl F22b 21/22 Field of Search 122/235,

{56] References Cited UNITED STATES PATENTS 1,816,434 7/1931 Kaemmerling 431/173 X 2,923,348 2/1960 Fraser 431/158 2,927,632 3/1960 Fraser 431/158 X 2,564,497 8/1951 Navias 431/1 RL 3,033,177 5/1962 Koch et a1... 122/235 Primary Examiner-Kenneth W. Sprague Attorney-Kenyon & Kenyon Reilly Carr & Chapin ABSTRACT: The steam generator is provided with a whirling combustion chamber capable of generating at least 10" kcaL/cubic meter hour ata. The whirling combustion chamber is connected directly to a combustion gas flue containing heating tubes or surfaces therein. The walls of the combustion chamber do not require cooling means as such are lined with ceramic oxide material.

STEAM GENERATOR AND OTHER HEATED HEAT TRANSMITTERS This invention relates to a steam generator or other heated heat transmitters.

Heretofore, steam generators have been known to employ large whirling combustion chambers with radiant-heat surfaces disposed on the walls of the combustion chambers for the combustion of various materials so that a considerable part of the heat of combustion becomes absorbed by the radiant-heat surfaces. in such installations, the resulting waste gases which have been cooled to a relatively great extent have then been conducted to connective or contact-heat surfaces. However, these large combustion chambers have required much space and, because of the possibility of explosions, have required an extensive and strong supporting structure. As a result, these components have formed expensive parts of the steam generator.

Other combustion chambers have been known such as cyclones and fusion combustion chambers in which coal dust has advantageously been burned in strong whirling currents to achieve increased performance. Generally, the outlet of such a cyclone combustion chamber has been contracted so that the larger unburned particles of coal or slag have been retained in the cyclone under centrifugal action while the combustion gases have flared out of the mouth of the cyclone into an adjacent combustion chamber lined with radiant-heat surfaces in which the combustion has then been completed.

These steam generators have further been known to be limited to average combustion chamber performances of the order of magnitude of 6x10 kcal./cubic meter per hour ata. although higher performances of up to 2X10 kcal./cubic meter per hour ata. can also be obtained with fire-tube boilers.

Combustion chambers having higher performances such as 10" kcaL/cubic meter hour ata. have been know for gas-turbine installations, chiefly for aircraft engines. However, in these installations, the combustion chamber walls have been cooled by a stream of air which has thereafter been added to the burning gas mixture. Further, the high combustion chamber performance has been achieved on the one hand through the use of easily volatilized fuels and on the other hand through a very great excess of combustion air, for example, in the range of from 1.2 to 3. Such combustion chambers, however, would be out of the question in plants in which the steam generator of the invention is to be used. This is due to the great waste-gas losses which would be obtained, the low gas-emergence temperature which would result in a substantial increase of the heating surfaces, and the great content of residual oxygen which, in the case of fuels containing sulfur, which would lead to an excessive formation of S0 (sulfur trioxide).

Further, while it may be possible to eliminate after combustion chambers in the case of steam generators having cyclone combustion chambers of conventional performance, this would lead to vary large and correspondingly expensive cyclone-type combustion chambers.

Accordingly, it is an object of this invention to decrease the size of steam generators and heated heat transmitters.

It is another object of the invention to provide a steam generator of low cost construction and high performance.

it is another object of the invention to utilize approximately stochiometric combustion in the combustion chamber of a high performance steam generator.

it is another object of this invention to obtain a high performance steam generator or heat transmitter.

it is another object of the invention to decrease the size of heating surfaces in a steam generator.

Briefly, the invention provides a steam generator with a whirling combustion chamber which is capable of performing at more than 10" kcaL/cubic meter/hour ata. and which is connected directly to a combustion gas flue having heating surfaces therein. In addition, any and all radiating combustion chambers are eliminated.

The whirling combustion chamber is utilized so that an approximately stochiometric mixture of fuel oil and/or gas with air is burnt therein and the resulting combustion gas is delivered directly to the combustion gas flue to contact the connective heating surfaces therein. The stochiometric combustion which takes place obtains an air excess of about 1.02.

It has been found that as a result of the use of the considerably higher heat-loading, a closed effective circuit is created. Further, through the supposedly unprofitable and dangerous step forward to higher working densities, the surface of the whirling combustion chamber can be decreased relative to its volume and thereby the emission of heat to the exterior becomes greatly diminished. Because of the smaller losses, the combustion temperature rises, which (together with the greater turbulence obtained in the whirling combustion chamber) leads to a more rapid combustion, through which, finally, the greater working density is obtained.

These and other objects and advantages of the invention will become more apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawing in which:

The FIGURE schematically illustrates a longitudinal sectional view of a forced-through flow steam generator according to the invention.

Referring to the drawings, the steam generator has a vertical combustion gas flue l, which is delimited laterally by four walls 2 formed of welded-together vertical tubes. These vertical tubes run from a distributor 3 at the lower inlets which forms a rectangular frame and have their upper outlets connected into an analogous rectangular collector 4. A bottom 5, having an insulation layer 6 thereover closes the bottom of the combustion gas flue 1 while the top of the flue l is connected, through the intermediary of pyramidlike connecting surfaces 7, with a chimney 8.

A plurality of horizontal tubular coils 12 forming a convective heating surface and connected in parallel are disposed in the combustion gas flue 1 between two collectors 10, 11 and a plurality of vertical tubular coils 13 connected in parallel and connected to two collectors 14, 15 hang over the horizontal coils 12. The collector 10 is supplied, through a pipe 16, with operating medium at above-critical pressure. This medium flows through the horizontal tubular coils l2, and from the collector 11 by way of a connecting pipe 17 into the distributor 3. After flowing through the vertical wall tubes, the operating medium flows out of the collector 4 through a connecting pipe 18 and into the collector l4, and from there through the tubular coils 13 to the collector 15, out of which the medium becomes conducted, through a line-steam conduit 19 to a steam-consumer.

In each of the four side walls 2 and below the tubular coils 12, a whirling-combustion chamber 20 is connected. Each whirling-combustion chamber 20 has an axis set horizontally and consists of a flame-tube 21 of cylindrical cross section having a ceramic oxide lining, and of a' coaxially disposed burner 22. in addition, the mouth of each combustion chamber 20 opens directly into the flue 1, as shown, without interruption from any heating surfaces to deliver the combustion gas directly from the chamber 20 into the flue 1 to flow directly over the tubular coil 12 which constitutes the first heating surface in the flue 1. The mouth of each combustion chamber 20 is of a diameter approximately equal to the largest internal diameter of the chamber 20.

Each whirling-combustion chamber 20 is constructed for a combustion chamber performance of more than 10" kcal./cubic meters hour ata.; that is, the actual burner 20 is dimensioned and constructed so that the quantity of heat liberated hourly in the cylindrical flame-tube 21 at atmospheric pressure relative to the internal volume of the cylindrical flametube 2.1, amounts to 10 kcalJcubic meter, as measured from the burner outlet as far as an imaginary plane disposed over the outlet opening. To this end, the tube 21 has a length to inner diameter ratio of from 0.5 to 2.0.

The whirling-combustion chambers are arranged in the opposite walls 2 on a common axis. As a result, the flames flaring out of one combustion chamber 20 extend for the greater part into the opposite combustion chamber thus leading to a higher temperature therein. That is, increased radiation out of the other combustion chambers also increases the temperature in the one concerned. By means of the coaxial arrangement of the combustion chambers, moreover, the wall areas subjected to direct flame-radiation becomes reduced. The free space in the combustion-gas flue 1 between the whirling-combustion chamber 20 should not in spite of the flame-radiation acting on the unobstructed parts of the walls, be confused with a radiation-burner chamber, because combustion is still confined within the whirling-combustion chamber 20.

The ceramic lining of the cylindrical flame-tube 21 of each whirling-combustion chamber 20 assumes a temperature at the inner surface practically equal to the temperature of the burning gases. Because of the low heat-conductivity of ceramics, and because of the supplementary insulation, the whirlingcombustion chambers 20 can thus be operated, up to a considerable size, without external cooling. Combustion can thus proceed practically adiabatically, which is quite essential for success.

An additional feature for obtaining as high a combustion temperature as possible is to greatly preheat the combustion air. This preheating is in practice limited since it would be a complicated matter to cool the parts of the burner 22 conducting the combustion air by a third medium, for example through the operating medium.

As shown, the combustion gas flue 1, without giving consideration to the dimensioning of the combustion chamber 20 can be dimensioned in accordance with the requirements for optimum heat transfer in the contact-heat surfaces. In the case of the contractions, noses and so forth, known with conventional boilers, these can thus be eliminated. A further advantage of the invention resides in that the highest heatstressed tubes, because of the uniform heating-up around the whole circumference and the stressless suspension, undergo only moderate heat-stresses. This permits a very high loading of the tubes, and this leads to a diminution of the heating area.

What I claim is:

1. ln combination with a steam generator having a combustion gas flue and a convective heating surface therein; at least one whirling combustion chamber of cylindrical shape with a circular cross section for the combustion of an approximately stochiometric mixture of fuel and air to produce an output of at least 10" kcaL/cubic meter per hour at atmospheric pressure, said combustion chamber being connected directly to said flue for delivery of combustion gas directly from said combustion chamber into said flue to flow directly over said convective heating surface.

2. The combination as set forth in claim 1 wherein said combustion chamber has an internal wall and a ceramic oxide lin' ing on said wall.

3. The combination as set forth in claim 1 wherein said combustion chamber has an uncooled wall.

4. The combination as set forth in claim 1 wherein said combustion chamber has a wall exposed to the mixture of fuel and air, and insulation about said wall to diminish heat loss therefrom.

5. The combination as set forth in claim 1 which includes an even number of said combustion chambers arranged in pairs coaxially opposite each other at one end of said flue.

6. The combination as set forth in claim 1 wherein said combustion chamber includes a flame tube of a length to inner diameter ratio of from 0.5 to 2.0.

7. The combination as set forth in claim 1 wherein said combustion chamber has a ceramic oxide lining therein.

8. The combination as set forth in claim 7 wherein said combustion chamber has insulation about said ceramic oxide lining to diminish heat loss therefrom.

9. The combination as set forth in claim 1 wherein said combustion chamber has a mouth openin into said flue, said mouth being uninterrupted and being 0 a diameter approxi- 

1. In combination with a steam generator having a combustion gas flue and a convective heating surface therein; at least one whirling combustion chamber of cylindrical shape with a circular cross section for the combustion of an approximately stochiometric mixture of fuel and air to produce an output of at least 107 kcal./cubic meter per hour at atmospheric pressure, said combustion chamber being connected directly to said flue for delivery of combustion gas directly from said combustion chamber inTo said flue to flow directly over said convective heating surface.
 2. The combination as set forth in claim 1 wherein said combustion chamber has an internal wall and a ceramic oxide lining on said wall.
 3. The combination as set forth in claim 1 wherein said combustion chamber has an uncooled wall.
 4. The combination as set forth in claim 1 wherein said combustion chamber has a wall exposed to the mixture of fuel and air, and insulation about said wall to diminish heat loss therefrom.
 5. The combination as set forth in claim 1 which includes an even number of said combustion chambers arranged in pairs coaxially opposite each other at one end of said flue.
 6. The combination as set forth in claim 1 wherein said combustion chamber includes a flame tube of a length to inner diameter ratio of from 0.5 to 2.0.
 7. The combination as set forth in claim 1 wherein said combustion chamber has a ceramic oxide lining therein.
 8. The combination as set forth in claim 7 wherein said combustion chamber has insulation about said ceramic oxide lining to diminish heat loss therefrom.
 9. The combination as set forth in claim 1 wherein said combustion chamber has a mouth opening into said flue, said mouth being uninterrupted and being of a diameter approximately equal to the largest internal diameter of said combustion chamber. 